The present invention relates to a washing machine of the vertical-axis type for the washing of fabric articles such as clothes, and more particularly to washing machines that have a system for detecting and correcting oversuds conditions during the wash cycle of operation.
Excessive suds build-up or oversudsing is a recognized problem for conventional agitator-type washing machines when operating in the spin mode. For orbital and horizontal axis tumbler-type washing machines the problem arises in both wash and spin operating modes. In order to achieve satisfactory washing results and to avoid excessive loading of the motor, a means for automatically detecting and correcting such conditions during the wash cycle is desirable. This need is particularly acute for orbital type machines such as, for example, that disclosed in U.S. Patent Application, Ser. No. 142,949, by John Bochan, filed Apr. 23, 1980 and now U.S. Pat. No. 4,328,600. In such machines, the rapid orbital motion of the basket within the tub subjects the air in the region between the bottom portion of the basket of the tub to a pumping action. When soapy liquid from the basket enters this region, it combines with the turbulent air to generate suds. When the detergent is sufficiently concentrated in this liquid from the basket, thick suds or foam build up rapidly to fill the tub and basket. In following its orbital path, the basket must shear and compress the foam between the tub and basket, placing a heavy and possibly excessive load on the motor.
U.S. Pat. No. 3,570,272 to Peyton W. Douglas discloses a system for suds lock elimination in agitator type machines. Suds locking as described by Douglas refers to the condition in which the detergent suds remain in the outside tub as water drains out, leaving a head of suds between the tub and the inner clothes basket. During spin the rotation of the inner basket churns the suds, causing the volume of suds to rapidly increase to the point of overflowing into the basket and possibly slowing down the basket. To eliminate the suds lock condition, Douglas proposes to spray the clothes and suds with water after the wash cycle is completed. Specifically, as taught by Douglas, the spin cycle is interrupted early in the cycle after the bulk of water has been removed but before excessive suds build up (approximately one minute). The motor is stopped by the timer for a brief pause (about 30 seconds) for deaeration of the suds. Spin of the basket is then re-initiated accompanied by water being sprayed over the clothes and suds for a predetermined period of one to two minutes to remove the suds from the machine. The timer then turns off the spray and spin continues to centrifugally remove the water from the clothes load. This basic sequence is automatically performed following every wash cycle whether or not excessive suds are actually present in the machine.
U.S. Pat. No. 4,091,833 to Ellis et al recognizes the problems of reduced efficiency of the washing action in a washing machine in the presence of excessive detergent foam which reduces the level of mechanical interengagement between materials being washed, as well as the inability of the washing solution to hold soiling matter in suspension when too little foam is present. In order to achieve the desired level of detergency in the machine, Ellis et al proposes a foam detecting system which monitors the electrical characteristics of the washing liquid to determine the amount of foam in the washing machine. The output signal from the foam detector is used to control the addition of detergent to provide a foaming condition corresponding to the desired detergency level. Specifically, Ellis et al teach actuating detergent dispensing valves to dispense detergent into the wash chabmer until the desired preselected foaming condition is achieved, then automatically closing the valves. Should the foaming condition subsequently fall below the desired condition, the system controls the admission of additional detergent to re-establish the desired condition.
While the Douglas patent and the Ellis et al patent deal with sudsing problems in washing machines, neither addresses the problem of automatically detecting and correcting oversuds conditions in a washing machine during the wash cycle.
It is therefore an object of the present invention to provide a washing machine employing means for detecting an oversuds condition in the washing machine during the wash cycle and means for interrupting normal wash cycle operation upon detection and initiating cyclical operation to correct such conditions before resuming normal cycle operation from the point of interruption.